Table 1.

Summary of recent advances in GQD synthesis, properties, and applications.

Starting material	Synthesis method	PL emission (nm)	Size (nm)	Application	References
Graphite rods	Electrochemical exfoliation	340-400	2.6±0.4	Facile synthesis of GQDs	[71]
Graphite rods	Electrochemical exfoliation	440-480	4	Tumor detection using pH-responsive change in PL	[131]
Graphite flakes	Microwave assisted liquid phase exfoliation	400-550	6	Synthesis without oxidation or reducing agents	[75]
Graphite	Graphite intercalated method	400-550	5	In vivo cell tracking	[122]
Fluorographene	Liquid exfoliation	N/A	10±2	MRI contrast agent	[52]
Carbon fiber	Chemical exfoliation	700-800	4.5±1.5	In vivo near-infrared imaging	[57]
Trisodium citrate	Pyrolysis	400-500	1.3±0.5	Fluorescence cell imaging	[16]
Citric acid, urea	Hydrothermal synthesis	410-470	12±2	Drug delivery for anticancer therapy	[11]
Vinylphenylboronic acid, boric acid	Solvothermal synthesis	370-530 420-530a)	5.8	MRI contrast agent	[51]
Nitropyrene	Hydrothermal synthesis	440-550	1-4	Cellular imaging via two-photon fluorescence microscopy	[113]
Pyrene	Hydrothermal synthesis	500-600	2.93±0.18	In vitro H2S sensor	[19]
Glucosamine, thiourea	Microwave assisted hydrothermal synthesis	448-539 800-890b)	3.9±2.0	One-step synthesis with microwave irradiation	[98]
Glucose	Hydrothermal synthesis	500-550	4.34	Detection of Cu2+ ions	[14]
Aminophenylboronic acid	Solvothermal synthesis	440-520 970-1020b)	4.7	In vivo imaging in the NIR-II window	[41]

^a)Two-photon excitation;

^b)NIR excitation